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1928 Roadster - Shifting Question


TFB3
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I'm fully aware that downshifting in a car this old is almost never going to work, but every so often I have an issue I wasn't expecting. On occasion, I have to shut the engine down to get it into first gear (or reverse). This doesn't happen all that often, but sometimes when I'm sitting at a stop sign with the clutch fully pressed to the floor, the transmission gears won't stop turning. Any attempt to get into gear is immediately met with the typical threat of grinding, so I try to wait it out. A few times I've waited well over a minute, but they just won't slow down. The only solution seems to be shut the engine down, slip it into first gear, restart the engine and go on as usual. Seems strange. Is this normal? Any suggestions if not?

 

 

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Clutch drag………try running a heavier oil. It’s probably only happening when hot………

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If your engine is tuned correctly you can use the retard lever to slow the engine down.  My 1925 Buick idles at 380 rpm on full advance, and 300 on full retard when it is warmed up.  When I come to a stop light, I do on ocassion have to retard the spark to get it to drop into 1st gear.  If the spark advance lever has no effect on your car's RPM, then you have issues we should discuss.  Your hand throttle needs to be operational as well.     

I am also running a blend of 60% Lucas 80/90 gear oil and 40% Lucas HD oil stabilizer in the transmission.  This blend is what the Model A club recommends as a modern replacement for 600W.  These 2 items are available at local auto parts stores and Walmart.  I have not had good luck shifting with old style 600W in the transmission.  

 

Buick Tune up notes

Plug gap is .030
Points .020 use 5.5 & 6 mm wrench to adjust and tighten points.
Dwell 26 degrees Sears @.020 gap
Dwell 28 Sears @.018 gap
Expected 35 degrees 
Set at 26 degrees 

Timing on 1-6 line at idle. (TDC)
Rpm 380 full advance
300 full retard

Timing at full advance idle -check
Timing full adv @ 2000 rpm-check

Vacuum 16 full retard.  
Vacuum 18-19 full advance
Leaning out (turning the fuel screw in) will raise the vacuum some - as high as 20.  If too lean it will backfire in the intake so need a richer mixture.  
Fuel mixture screw set at 3/4 open. 

Temperature hovers at 220 degrees on long trips at 45 mph
High temp Alarm at 240 F

Firing order 1-4-2-6-3-5 CW

Look at plug wires at night 

 

Hugh

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3 hours ago, edinmass said:

Clutch drag………try running a heavier oil. It’s probably only happening when hot………

Yes! It’s much worse when hot. I’m running Amsoil SAE 250 though. What’s heavier??? I could try asphalt I suppose LOL. 

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2 hours ago, Hubert_25-25 said:

My 1925 Buick idles at 380 rpm on full advance, and 300 on full retard when it is warmed up. 

Thanks Hugh, You’ve given me an idea. I have no idea what RPMs I’m running at idle but I’d guess I’m at least 800. Sounds like I need to drop the idle and see what happens. 

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Don: Thanks for the video. While looking thru some of the other 1927 Buick starting/running videos there is one that looks to be of a model 50. That engine sounds terrible. Yours sounds lovely with the transmission singing along happily!

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Quick Update: 

 

I reduced the idle from 700 to 360 and retarded the timing a bit more. Now for the first time, the spark lever produces a noticeable RPM difference from top to bottom. Using a timing light, I can see that I'm at 22° / 460 rpm at full advance and 0° / 360 rpm at full retard. My vacuum has dropped three pounds to 16 lbs; undoubtedly the result of dropping the idle from the previous 700 rpm.

 

The new lower idle definitely helps get into gear while stopped, but it still protests every so often when hot, so I'll probably try the 2:1 mix of Lucas 80/90 and Oil Stabilizer that everyone talks about. I've also dropped my shift points way down so I'm into 2nd at about 5mph and into 3rd at about 10mph; it's much more cooperative! I do still get the occasional engine burp while underway, but it's only when hot and it seems to go away when I increase the advance to maximum. I can also report that the hot idle now seems stable and smooth. 

 

For someone who's accustomed to listening to modern engines, it's amazing how much more of the mechanical sounds you can clearly hear in an old-fashioned, long stroke engine when it's running at 360 rpm. :)  I'm definitely making progress. Thanks for all the help. I'm sure I'll have more to report in the coming days. 

Edited by TFB3 (see edit history)
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It sounds like you have made great progress.  Have you replaced the venturi block in your carburetor?  I would like to get your vacuum reading from 16 back up to 18 at idle.  If you are back to 18 inches with just a little pressure on the gas pedal, then you are pretty close.  That may require turning the air valve in a little and adjusting the mixture needle to compensate. You are working with 3 things.   The idle stop, mixture screw, and air valve spring pressure.  The more you can back out the idle stop screw, the more the butterfly is closed, and this will increase the vacuum reading.    Hugh       

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The learning curve to shift is just as important as dialing the car in.......you're very close. And while we all try for perfection, zipping a gear today with modern traffic conditions sometimes can't be helped. Nice car......

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I've found leaving it in high gear until I come to a complete stop (clutch in as I stop, of course) then moving it to first after I've come to a stop is a lot easier because the cluster gears have stopped spinning (since high gear is direct drive). Clutching in and putting it in neutral as you coast to a stop means all the gears are still spinning when you go to put it into first. Try it and see if things improve.

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